The present invention generally relates to the field of rotary cutting tools such as milling tools, also known as milling cutters.
The invention also concerns the field of machining methods using such tools, in particular but not exclusively machining methods employed in the area of aeronautical constructions. By way of indication, the methods in question may in particular be methods for producing parts of engines intended to equip aircraft.
In the prior art, the machining methods aimed at obtaining such parts of complex geometry often require the use of a multitude of successive machining steps, and more specifically of a number of milling steps during which the tool used is moved with a circular cutting movement about its own longitudinal axis, and the workpiece to be machined is moved with any desired relative feed movement with respect to this tool.
In order to best optimize this type of method, it is known to a person skilled in the art to prefer a machining operation in “climb mode” rather than in “conventional mode”, these two modes being defined not only as a function of the direction of rotation of the tool, itself governed exclusively by the orientation of the helical cutting teeth equipping this tool, but also as a function of the direction of the relative feed between this cutting tool and the workpiece to be machined.
In light of the foregoing, it is clear that during the use of the method for machining a workpiece, when the direction of relative feed between the cutting tool and the workpiece is imposed by the workpiece geometry, the fact of wishing to work with preference in the climb mode imposes a direction of rotation of the tool. That may therefore result in the need to employ a different tool from the one used in the preceding machining step whenever this previously used tool was designed to rotate in the direction of rotation opposed to the new direction of rotation required.
This constraint of changing tools during the machining of one and the same workpiece is clearly extremely penalizing in terms of production times and costs, this disadvantage being of course all the more constraining when the number of separate machining steps to be carried out is high.
Moreover, when the direction of relative feed between the cutting tool and the workpiece is not imposed and can thus be freely chosen by the operator as a function of the direction of rotation of the tool and so as to allow working in climb mode, it may nevertheless occur that the overall cutting force generated during this machining step does not result in the workpiece being applied against the positioning rests conventionally provided on the machine but, on the contrary, in this same workpiece being applied against clamping means which equip the machine and complement the positioning rests.
This latter configuration is clearly not desired in the sense that it does not allow good positioning of the workpiece to be maintained during the machining, this disadvantage being manifested by losses in terms of cutting quality and precision.
Consequently, to allow working in climb mode and moreover generate an overall cutting force resulting in the workpiece being applied against the positioning rests and not against the clamping means, it would probably be required in this case too to have recourse to a change of tool in favour of a tool having an opposed direction of rotation. Nevertheless, that would involve being exposed to the aforementioned disadvantages relating to the tool-changing operations.